Formed on 18 July 1917 and activated 22 August 1917 at Camp Edwards, MA, consisting of units from the New England area, the division's commander selected the nickname "Yankee Division" to highlight the division's geographic makeup. Sent to Europe in World War I as part of the American Expeditionary Forces, the division saw extensive combat in France. Sent to Europe once again for World War II, the division again fought through France, advancing into Germany and liberating the Gusen concentration camp before the end of the war.

Following the end of World War II, the division remained as an active command in the National Guard, gradually expanding its command to contain units from other divisions which had been consolidated. However, the division was never called up to support any major contengencies or see major combat, and was eventually deactivated in 1993, reorganized as a brigade under the 29th Infantry Division.

On 21 September 1917, the division arrived at Saint-Nazaire, France.[5] It was the second division of the American Expeditionary Force (AEF) to arrive on the Western Front at the time, and the first division wholly organized in the United States, joining the 1st Division. Two additional divisions completed the first wave of American troop deployment, with the 2nd Division formed in France and the 42nd Division arriving at St. Nazaire on 29 October.[6] The division immediately moved to Neufchâteau for training, as most of the division's soldiers were raw recruits, new to military service.[6] Because of this, much of the division's force was trained by the experienced French forces.[7] It trained extensively with the other three US divisions, organized as the U.S. I Corps in January 1918,[6] before being moved into a quiet sector of the trenches in February.[8]

The 26th Infantry Division remained in a relatively quiet region of the lines along the Chemin des Dames for several months before it relieved the 1st Division near St. Mihiel on 3 April. The line here taken over extended from the vicinity of Apremont, on the west, in front of Xivray-Marvoisin, Seicheprey, and Bois de Remieres, as far as the Bois de Jury, on the right, where the French line joined the American line. Division Headquarters were at Boucq.

The stay of the division in this sector was marked by several serious encounters with the enemy, where considerable forces were engaged. There were furthermore almost nightly encounters between patrols or ambush parties, and the harassing fire of the artillery on both sides was very active.

On 10, 12 and 13 April, the lines held by the 104th Infantry in Bois Brule (near Apremont), and by the French to the left, were heavily attacked by the Germans. At first the enemy secured a foothold in some advanced trenches which were not strongly held, but sturdy counterattacks succeeded in driving the enemy out with serious losses, and the line was entirely re-established.

In late April, German infantry conducted a raid on positions of the 26th Division, one of the first attacks on Americans during the war. At 0400 on 20 April, German field artillery bombarded the 102nd Infantry's positions near Seicheprey before German stoßtruppen moved against the village. The artillery box barrage, continuing 36 hours, isolated American units. The Germans overwhelmed a machine gun company and two infantry companies of the 102nd and temporarily breached the trenches before elements of the division rallied and recaptured the village. The Germans withdrew before the division could counterattack but inflicted 634 casualties, including 80 killed, 424 wounded, and 130 captured, while losing over 600 men, including 150 killed of their own.[9] Similar raids struck the 101st infantry at Flirey on 27 May, and the 103rd Infantry at Xivray-et-Marvoisin on 16 June, but were repulsed. The 26th Division was relieved by the 82nd Division on 28 June, moved by train to Meaux, and entered the line again northwest of Chateau Thierry, relieving the 2nd Division on 5 July.

As the size of the AEF grew, the division was placed under command of I Corps in July.[10] When the Aisne-Marne campaign began shortly thereafter, the division, under I Corps was placed under command of the French Sixth Army protecting its east flank. When the offensive began, the division advanced up the spine of the Marne salient for several weeks, pushing through Belleau Wood, moving 10 miles from 18 to 25 July. On 12 August it was pulled from the lines near Toul to prepare for the next offensive.[11] The division was then a part of the offensive at St. Mihiel, during the Battle of Saint-Mihiel. The division then moved in position for the last major offensive of the war, at Meuse-Argonne. This campaign was the last of the war, as an armistice was signed shortly thereafter.[12] During World War I the 26th Division spent 210 days in combat, and suffered 1,587 killed in action and 12,077 wounded in action.[5] The division returned to the United States and was demobilized on 3 May 1919 at Camp Devens, Massachusetts.[1]

In the years following World War I, the division remained in the National Guard, seeing periodic reorganizations but no major deployments except for weekend training. In 1921, the 102nd Infantry was replaced in the guard by the 182nd Infantry. In 1923, the 103rd Infantry was replaced with the 181st Infantry.[2] In 1941, during World War II, although the United States was still neutral, the 101st Infantry was replaced with the 164th Infantry briefly; one year later it was relieved from the division, along with the 182nd Infantry, in order to form the Americal Division.[2]

As a part of an army-wide reorganization, the division's brigade headquarters were disbanded in favor of regimental commands. The division was instead based around three infantry regiments; the 101st, 104th, and the 328th.[13] Also assigned to the division were the 101st, 102nd, 180th, and 263rd Field Artillery Battalions, the 39th Signal Company, the 726th Ordnance Company, the 26th Quartermaster Company, the 26th Reconnaissance Troop, the 101st Engineer Combat Battalion, and the 114th Medical Battalion.[13] In August 1943 Major General Willard Stewart Paul took command of the division, which he would lead through the rest of the war.[14] Before deploying overseas to the European Theater of Operations (ETO), the 26th ID trained at Camp Campbell, Kentucky and prepared to depart for the Western Front in late August 1944.

Rest at Metz was interrupted by the German offensive in the Ardennes, the Battle of the Bulge. The division moved north to Luxembourg from 19 to 21 December, to take part in the battle of the Ardennes break-through. It attacked at Rambrouch and Grosbous on 22 December, beat off strong German counterattacks, captured Arsdorf on Christmas Day after heavy fighting, attacked toward the Wiltz River, but was forced to withdraw in the face of determined German resistance. After regrouping on 5–8 January 1945, it attacked again, crossing the Wiltz River on 20 January.[17] The division continued its advance, taking Grumelscheid on 21 January, and crossed the Clerf River on 24 January. The division was reassigned to XX Corps.[15] The division immediately shifted to the east bank of the Saar, and maintained defensive positions in the Saarlautern area from 29 January until 6 March 1945.

The division's drive to the Rhine River jumped off on 13 March 1945, and carried the division through Merzig from 17 March, to the Rhine by 21 March, and across the Rhine at Oppenheim on 25–26 March.[17] The division was then reassigned to XII Corps.[15] It took part in the house-to-house reduction of Hanau on 28 March, broke out of the Main Riverbridgehead, drove through Fulda on 1 April, and helped reduce Meiningen on 5 April. Moving southeast into Austria, the division assisted in the capture of Linz, 5 May. It had changed the direction of its advance, and was moving northeast into Czechoslovakia, across the Vlatava River, when the cease-fire order was received.[17] One day later, the division overran the Gusen concentration camp in conjunction with the 11th Armored Division, liberating it from German forces. There, it discovered that the Germans had used forced labor to carve out an elaborate tunnel system with underground aircraft production facilities. SS officers at the camp allegedly planned to demolish the tunnels with the prisoners inside, but the movement of the 26th Infantry and 11th Armored Divisions prevented this.[19]

The division was reactivated on 11 April 1947 in Boston.[1] It remained as the major command of the Massachusetts Army National Guard, but its command took control of units from other states following consolidation of the Army National Guard. The division remained as an active reserve component of the Army National Guard, but it was not selected for any deployments to cold war contingencies.[12] In 1956 the division received its distinctive unit insignia.[4]

The division was reorganized in accordance with the Pentomic organization, probably in 1959. Among the battle groups of the division were 1st Battle Group, 101st Infantry, and 1st Battle Group, 182nd Infantry. The 104th Infantry Regiment was reorganized on 1 May 1959 under the Combat Arms Regimental System as the 1st Battle Group, 104th Infantry.

In 1963, the division was reorganized under the Reorganization Objective Army Division plan. Its regimental commands were inactivated in favor of brigades. The 101st Infantry Regiment became the 1st Brigade, 26th Infantry Division, headquartered in Dorchester, Massachusetts. The 104th Infantry Regiment became the 3rd Brigade, 26th Infantry Division, headquartered in Springfield, Massachusetts. Among the division's units in 1965 were the 1-101 infantry, 1-104, 2-104, 1-181, 1-182, 1-220 Infantry, and 1-101 FA.[22] The division was organized as a light infantry division, and at the same time, the 26th Aviation Battalion was established to provide air support. In 1967 the 43rd Infantry Division of the Connecticut Army National Guard was consolidated into the 43rd Brigade, 26th Division, and put under the command of the 26th Infantry Division.[23]

In 1987, the 26th Aviation Battalion was dissolved and the 126th Aviation Regiment arose in its place. The 126th Aviation Regiment's battalions formed the basis of the new divisional 26th Aviation Brigade.

On 1 April 1988, the division was relocated to Camp Edwards, Massachusetts.[1] The division headquarters was consolidated with 1st Brigade, 26th Infantry Division.[24] In its place, the 86th Infantry Brigade was assigned to the division as a round-out unit.[23]

Following the end of the Cold War, the Army began a process of downsizing its forces. The Army reactivated the 29th Infantry Division and began reorganizing its forces and further consolidating them. As a result, the Army decided to downsize the 26th Infantry Division into a brigade, and put it under the command of the 29th Infantry Division.[12] On 1 September 1993, the division was inactivated, and the 26th Infantry Brigade designated in its place, based in Springfield.[1] The 3rd and 43rd brigades, 26th Infantry Division were inactivated, and the 86th Infantry Brigade was put under the command of the 42nd Infantry Division.[23] On 1 October 1995, the division was formally designated the 26th Brigade, 29th Infantry Division.[25] In 2004, the 26th Brigade transitioned into the 26th (Yankee) Infantry Brigade Combat Team.

The beltway around the city of Boston, Massachusetts Route 128, is nicknamed the "Yankee Division Highway" in honor of the 26th Infantry Division.[27] For its contribution in liberating the Gusen concentration camp, the United States Holocaust Memorial Museum continually flies the division's colors at its entrance and for high-profile memorial ceremonies, honoring it as one of 35 US divisions to have assisted in the liberation of German concentration camps.[28]